property path length restrictions [was: Re: A review of extension functions in current implementatations]

Dear all,

something I find myself missing almost every time I work with SPARQL is  
the path length feature in the early property graph drafts:
elt{n,m}	A path between n and m occurrences of elt.


What I normally use instead is aggegation and counting of intermediate  
nodes, in order to have it portable, so I didn't check for current  
implementations. Not sure whether this qualifies for the wiki, thus, but  
there used to be implementations 10 years ago:  
https://www.w3.org/2009/sparql/wiki/Feature:PathLength

The aggregation solution works in most cases (it is slow, though), but  
this is a pain to write and to teach -- and a needless one if path length  
would be implemented just as syntactic sugar for aggregate+count.

Best,
Christian

Am .04.2019, 23:51 Uhr, schrieb Jeen Broekstra <jeen.broekstra@gmail.com>:

> Thanks for this Jerven.
> I added a short list of things I could think of from the top of my head  
> that RDF4J currently adds as SPARQL extensions. I also mentioned  
> GeoSPARQL for >completeness sake, although I think we should probably  
> consider such an elaborate feature (with its own set of specs) out of  
> scope. Feel free to extend, >correct, or ask for clarification (I've  
> been rather terse in my examples).
>
> Jeen
>
> On Thu, Apr 4, 2019 at 5:54 AM Jerven Tjalling Bolleman  
> <Jerven.Bolleman@sib.swiss> wrote:
>> Hi Adrian, Bob, All,
>>
>> I created a wiki page at 
>> https://github.com/w3c/sparql-12/wiki/Inventory-of-existing-extensions-to-SPARQL-1.1
>>
>> That you can start with.
>>
>> Adrian, I added you as a collaborator in case that is needed.
>>
>> Bob, I don't know your github account so please let me know if me or 
>> Andy needs to do some
>> admin work for you.
>>
>> This goes for anyone whom would like to work on this and can't due to
>> permissions.
>>
>> Regards,
>> Jerven
>>
>>
>> On 2019-04-03 19:38, Adrian Gschwend wrote:
>>> On 03.04.19 18:58, bob@snee.com wrote:
>>>Hi Bob,
>>>
>>>> Instead of assigning a single person to do an inventory of these
>>>> functions someone (I'd be happy to) could serve as an editor of a
>>>> summary document with content provided by those implementors. If there
>>>> is no place under 
>>>> https://lists.w3.org/Archives/Public/public-sparql-12/
>>>> where we can put a page to store such a document perhaps git would be
>>>> the best place for it.
>>>that definitely makes sense! And if you volunteer you get a +1 from me
>>> :) Would add some stuff I have in mind as well.
>>>regards
>>>Adrian
>>
>> --Jerven Tjalling Bolleman
>> SIB | Swiss Institute of Bioinformatics
>> CMU - 1, rue Michel Servet - 1211 Geneva 4
>> t: +41 22 379 58 85 - f: +41 22 379 58 58
>> Jerven.Bolleman@sib.swiss - http://www.sib.swiss
>>
>>



-- 
Prof. Dr. Christian Chiarcos
Applied Computational Linguistics
Johann Wolfgang Goethe Universität Frankfurt a. M.
60054 Frankfurt am Main, Germany

office: Robert-Mayer-Str. 11-15, #107
mail: chiarcos@informatik.uni-frankfurt.de
web: http://acoli.cs.uni-frankfurt.de
tel: +49-(0)69-798-22463
fax: +49-(0)69-798-28334